Various polymer products have gained many structural applications such as in the construction and transportation industries. In addition, uses are made of many polymer products in fabrics, upholsteries, wallcoverings and the like where flame resistance and smoke formation can be a problem in the event of fire. New governmental and safety regulations relating to such materials are now in effect, requiring not only increased flame resistance but reduced smoke generation from such plastic materials in certain applications, further requiring that such properties be present not only in open burning but also in smoldering states.
A vast amount of research has been carried out to increase flame resistance and reduce smoke in such plastic materials, but further improvement continues to be required in order to make such materials suitable for many applications.
One class of materials long proposed to reduce smoke has been the use of molybdenum compounds, usually in conjunction with other compounds such as antimony oxide, in order to reduce the tendency to burn as well as the amount of smoke generated when combustion of such plastic materials is encountered.
While the vast amount of art available prohibits any detailed discussion of each article or reference, representative but non-exhaustive examples of the prior art dealing with the use of molybdenum compounds in various polymer formulations are set forth below.
U.S. Pat. No. 3,845,001 teaches that copper compounds alone or admixed with molybdenum compounds impart smoke retardant properties to combustible materials such as plastics, including polyvinyl chloride. U.S. Pat. No. 3,900,441 teaches that the smoking tendencies of PVC under combustion conditions is reduced by the use of a combination of zinc and molybdenum compounds. U.S. Pat. No. 3,914,201 indicates that polyvinyl chloride compositions are rendered more flame and smoke retardant by the use of compounds such as MoS.sub.2 and Si.sub.3 N.sub.4 and mixtures of these. U.S. Pat. No. 3,983,086 teaches that smoke retardancy can be imparted to polyvinyl chloride compositions by utilizing nickel compounds in combination with iron compounds including iron molybdate. U.S. Pat. No. 4,053,453 teaches that copper oxylate and amine molybdates in combination provide smoke suppression to polyvinyl chloride compositions which are burned. U.S. Pat. No. 4,055,537 teaches that smoke retardant polyvinyl chloride compositions are obtained by a synergistic mixture of melamine molybdate and certain zinc, borate, manganese and tungsten oxide compounds. U.S. Pat. No. 4,098,753 teaches that ester-type plasticizers and inorganic molybdenum compounds provide smoke suppression to plasticized polyvinyl chloride. U.S. Pat. No. 4,133,823 teaches that the reaction products of metal oxides, such as molybdenum oxides and phosphorus compounds in a trivalent state provide flame and smoke suppression. U.S. Pat. No. 4,328,152 teaches that a combination of zinc phosphates and zinc molybdate compounds provide smoke suppression in polyvinyl chloride.
In addition, several papers published by the Climax Molybdenum Company, Ann Arbor, Michigan, show that molybdenum compounds can be effective smoke suppressants for both plasticized and rigid PVC compounds. In Plastic Engineering, 1975, 31(12), 36-8, molybdenum trioxide and ammonium molybdates were taught to be flame retardants and smoke suppressants for PVC. In the Society for Plastic Engineering Technical Papers, 1977, No. 23, pp. 414-416, molybdenum compounds were taught to be effective smoke suppressants for rigid and plasticized PVC. In Fire Retardant Proceedings; The International Symposium, Flammability Fire Retardants, 1976, pp. 216-227, molybdenum compounds were taught to be effective fireproofing agents and smoke suppressants for flexible PVC, especially in combination with antimony oxide.